bscan: rename from bscan_spi, add TAP primitives for the SVF player

The module outgrew its "SPI bridge" name — it's mostly generic
single-device JTAG TAP primitives now. Rename modules/bscan_spi ->
modules/bscan (dir, files, library target, includes, doc paths);
bscan_* function names and bscan_spi_xfer() kept.

Add the two primitives the SVF player needs beyond shift_dr:
- bscan_shift_ir: general IR scan with TDO capture (bscan_set_ir is
  opcode-only, no readback)
- bscan_tap_reset: force Test-Logic-Reset, land in Run-Test/Idle

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

modules/bscan/CMakeLists.txt

@@ -4,4 +4,4 @@ file(GLOB_RECURSE ALL_SOURCES "*.c")
 
 include_directories(${CMAKE_CURRENT_SOURCE_DIR}/..)
 
-add_library(bscan_spi ${ALL_SOURCES})
+add_library(bscan ${ALL_SOURCES})

modules/bscan/bscan.c

@@ -2,7 +2,7 @@
 #include <stdlib.h>
 #include <string.h>
 
-#include "bscan_spi.h"
+#include "bscan.h"
 
 /* JTAG byte format expected by drv_TXRX_DATA / drv_TX_TMS:
  *   bit 0 (JTAG_STR_DOUT) = TDI value
@@ -108,6 +108,78 @@ int bscan_shift_dr(jtag_core *jc, const uint8_t *tdi, uint8_t *tdo, int nbits)
     return 0;
 }
 
+int bscan_shift_ir(jtag_core *jc, const uint8_t *tdi, uint8_t *tdo, int nbits)
+{
+    unsigned char tms_buf[8];
+    unsigned char *buf_out, *buf_in;
+    int i;
+
+    if (!drv_ok(jc) || nbits <= 0) {
+        return -1;
+    }
+
+    /* Idle -> Select-DR -> Select-IR -> Capture-IR -> Shift-IR */
+    tms_buf[0] = JTAG_STR_TMS;
+    tms_buf[1] = JTAG_STR_TMS;
+    tms_buf[2] = 0;
+    tms_buf[3] = 0;
+    jc->io_functions.drv_TX_TMS(jc, tms_buf, 4);
+
+    buf_out = malloc(nbits);
+    if (!buf_out) return -1;
+    buf_in = tdo ? malloc(nbits) : NULL;
+    if (tdo && !buf_in) { free(buf_out); return -1; }
+
+    for (i = 0; i < nbits; i++) {
+        uint8_t bit = 0;
+        if (tdi) {
+            bit = (tdi[i / 8] >> (i & 7)) & 1u;
+        }
+        buf_out[i] = bit ? JTAG_STR_DOUT : 0;
+        if (i == nbits - 1) {
+            buf_out[i] |= JTAG_STR_TMS;     /* last bit -> Exit1-IR */
+        }
+    }
+    jc->io_functions.drv_TXRX_DATA(jc, buf_out, buf_in, nbits);
+
+    if (tdo && buf_in) {
+        memset(tdo, 0, (size_t)((nbits + 7) / 8));
+        for (i = 0; i < nbits; i++) {
+            if (buf_in[i]) {
+                tdo[i / 8] |= (uint8_t)(1u << (i & 7));
+            }
+        }
+    }
+
+    free(buf_out);
+    free(buf_in);
+
+    /* Exit1-IR -> Update-IR -> Idle */
+    tms_buf[0] = JTAG_STR_TMS;
+    tms_buf[1] = 0;
+    jc->io_functions.drv_TX_TMS(jc, tms_buf, 2);
+
+    return 0;
+}
+
+int bscan_tap_reset(jtag_core *jc)
+{
+    unsigned char tms_buf[8];
+
+    if (!drv_ok(jc)) return -1;
+
+    /* 5 TMS=1 forces Test-Logic-Reset from any state, then 1 TMS=0
+     * lands in Run-Test/Idle (where the shift primitives start). */
+    tms_buf[0] = JTAG_STR_TMS;
+    tms_buf[1] = JTAG_STR_TMS;
+    tms_buf[2] = JTAG_STR_TMS;
+    tms_buf[3] = JTAG_STR_TMS;
+    tms_buf[4] = JTAG_STR_TMS;
+    tms_buf[5] = 0;
+    jc->io_functions.drv_TX_TMS(jc, tms_buf, 6);
+    return 0;
+}
+
 int bscan_idle_cycles(jtag_core *jc, int ncycles)
 {
     unsigned char *buf;

modules/bscan/bscan.h

@@ -1,22 +1,23 @@
-#ifndef _BSCAN_SPI_H
-#define _BSCAN_SPI_H
+#ifndef _BSCAN_H
+#define _BSCAN_H
 
 /*
- * BSCAN-proxy SPI bridge (Phase 2.5).
+ * Single-device JTAG primitives and BSCAN-proxy operations.
  *
  * Provides:
- *   - low-level JTAG primitives (set_ir, shift_dr, idle_cycles) that
- *     operate directly on jc->io_functions, leaving jtag_core untouched;
+ *   - low-level JTAG TAP primitives (set_ir, shift_ir, shift_dr,
+ *     idle_cycles, tap_reset) that operate directly on jc->io_functions,
+ *     leaving jtag_core untouched. These are the building blocks the SVF
+ *     player and the proxy paths share;
  *   - bitstream loading via CFG_IN to install a BSCAN proxy in the FPGA
- *     fabric;
+ *     fabric (Xilinx);
  *   - a fast SPI transfer routine via USER1 once the proxy is loaded.
  *
+ * (Was modules/bscan_spi/ — renamed once it grew past the SPI bridge
+ * into general TAP primitives.)
+ *
  * Current assumption: single device on the JTAG chain. Multi-device
  * support requires knowing the IR length of bypassed devices; defer.
- *
- * The SPI transfer entry point is wired against the quartiq jtagspi
- * proxy convention but the protocol header still needs to be confirmed
- * against an actual proxy bitstream (see openocd src/flash/nor/jtagspi.c).
  */
 
 #include <stddef.h>
@@ -34,6 +35,11 @@ int bscan_set_ir(jtag_core *jc, unsigned int opcode, int ir_length);
  * `tdo` may be NULL (write only). Both buffers are LSB-first per byte. */
 int bscan_shift_dr(jtag_core *jc, const uint8_t *tdi, uint8_t *tdo, int nbits);
 
+/* Like bscan_shift_dr but through Shift-IR — a general IR scan with TDO
+ * capture (bscan_set_ir is opcode-only). Single-device chain; buffers
+ * LSB-first per byte. Both ends in Run-Test/Idle. */
+int bscan_shift_ir(jtag_core *jc, const uint8_t *tdi, uint8_t *tdo, int nbits);
+
 /* Emit `ncycles` TCK cycles while staying in Run-Test/Idle. */
 int bscan_idle_cycles(jtag_core *jc, int ncycles);
 

modules/script/script.c

@@ -39,7 +39,7 @@
 #include "os_interface/os_interface.h"
 #include "fpga/fpga.h"
 #include "probes/probes.h"
-#include "bscan_spi/bscan_spi.h"
+#include "bscan/bscan.h"
 #include "spi_flash/spi_flash.h"
 
 #include "env.h"